Effect of Foliar Fertilizer and Irrigation Levels on Carrot Productivity

Carrot (Daucus carota L.) productivity is still low in Tanzania due to inadequate management. There is dearth of information from the literature on the best management practices with respect to irrigation water (IW) and fertilizer levels for optimal carrot production. Consequently, farmers have limited access to means of boosting carrot productivity levels. Thus, a study was conducted to evaluate the effect of various levels of irrigation for carrots using drip irrigation and their interaction with carbonate foliar fertilizer (Lithovit standard) on the growth, yield, and sugar content of carrots at the School of Engineering and Technology (SoET) research field, Sokoine University of Agriculture (SUA) in Morogoro region, Tanzania. Crop water requirement (ETc) was calculated using established procedures upon which water application levels were based. Foliar fertilizer was applied at levels of 1 (F1), 1.5 (F2), and 2 (F3) g/L/plant, while irrigation levels applied were 60 (I1), 80 (I2), and 100 (I3) percent of ETc. The experiment was a 3x3 factorial with treatment combinations F1I1, F1I2, F1I3, F2I1, F2I2, F2I3, F3I1, F3I2, and F3I3 conducted over two seasons during 2020/2021 and 2021/2022. The highest yield of 30.9 t ha-1 of carrots was obtained under 100% ETc, and the lowest yield of 15.1 t ha-1 was obtained under the 60% ETc. Carrots under a deficit irrigation water level of 20%, i.e., 80% ETc were found to have the highest content of sugar. On the other hand, the highest yield of 26.1 t ha-1 of carrots was obtained under the 2 g/L/plant fertilizer level, and the lowest yield of 17.9 t ha-1 of carrots was obtained under the 1 g/L/plant fertilizer level. Carrots under the 1.5 g/L/plant fertilizer level were found to have the highest content of sugar. Therefore, for optimum growth and yield, full irrigation in combination with foliar fertilizer application at a level of 2 g/L/plant is recommended for carrots under Morogoro conditions. However, for high sugar content, irrigation at 80% ETc in combination with foliar fertilizer application at a level of 1.5 g/L/plant is recommended.